Pescatarian Diet vs. Vegetarian Diet: What's the difference?Both a vegetarian and a pescatarian diet plan mainly rely on plant-based foods like whole grains, legumes, vegetables, fruits, nuts and seeds. While pescatarian meal plans include fish, vegetarians choose not to eat seafood, poultry, beef, or other kinds of meats. This often provides pescatarians additional flexibility when it comes to getting protein in their diet, or when dining out.